Generally, passenger service units (PSU) are installed close to a passenger seat, for example above a passenger seat to provide entertainment and safety services to the passenger. A PSU may contain different devices and may comprise these devices for a single or a plurality of passengers. Usually, a PSU comprises a display unit for providing safety information to a passenger, a reading light and a ventilation nozzle. Furthermore, an interface may be present for requesting help by the cabin crew or the like.
Furthermore, besides such a PSU, an emergency oxygen device may be installed in an aircraft. Such emergency oxygen device serves to provide oxygen to a passenger in case of an emergency like a decompression situation. In such case, oxygen flow from an oxygen source is provided by said emergency oxygen device to an oxygen mask which can be worn by the passenger. For this purpose, the oxygen flow must be started which can be done by different starter units, some of which require electrical energy for activation. Further, during use of the emergency oxygen device and supply of the oxygen a pressure and amount of the oxygen shall be controlled by a control unit included in the emergency oxygen device which very often requires electrical energy.